A. Field of the Invention
This invention relates to a method for securing a carrier, and more particularly relates to a method for securing a carrier by gas pressurization to inhibit warpage of the carrier.
B. Description of the Prior Art
Warpage of a package results from different thermal expansion coefficients of different materials in the package. To overcome the warpage problem, various methods have been disclosed in the field of packaging. Taiwan Patent No. I259743, for example, discloses disposing a plurality of non-functional traces inside a substrate so as to utilize the counteraction of stresses generated by the non-functional traces to maintain the flatness of the substrate. However, this method may complicate the circuit layout and thus makes it difficult to perform the circuit layout inside the substrate. Besides, Taiwan Patent Publication No. 489496, for instance, discloses disposing a glue bank, having a thermal expansion coefficient higher than that of the substrate, on the substrate so as to inhibit the warpage of the substrate. Nevertheless, since the glue bank still remains inside the manufactured semiconductor package after the process, the surface of the substrate needs to reserve an area for disposing the glue bank, which prevents further miniaturization of package size. Additionally, for example, Taiwan Patent No. I231578 discloses disposing a plurality of stiffening members under a substrate and using a stiffener encapsulant encapsulating the stiffening members, thereby inhibiting the warpage of the substrate. However, because each stiffening member should correspond to the peripheral of the chip-disposing region of the substrate, it is difficult to align while disposing the stiffening members. Especially, if there are more chip-disposing regions on the substrate, the alignment of the stiffening members gets even more complicated, which prevents miniaturizing package size and wastes the substrate. Moreover, Taiwan Patent No. I340446 discloses that a substrate is fixed by adhering temporary stiffeners to a trash portion of the substrate so as to counteract the warpage generated due to the thermal expansion of the substrate, and the temporary stiffeners are cut and removed in the last stage of the process. Furthermore, similar to the method of the aforementioned Patent No. I340446, Taiwan Patent No. I352395, for instance, discloses that a double-sided tape is temporarily adhered to secure a substrate to a hard and heat-resistant carrier through the tape, and the temporarily adhered double-sided tape and the carrier are removed in the last stage of the process. Although the above methods can overcome the warpage problem of a substrate in the process, those methods complicate the process and increase the manufacturing cost. Considering problems the above conventional technologies encounter, a method which can inhibit warpage of a carrier is urgently required.